Science can be confusing. It is always evolving. Rarely do good scientists speak in absolute terms. Rather than declare that A is definitely NOT causal to B, it is more honest to say that based upon the data so far (which may be limited to biased experimental designs) there is no evidence that A is causal to B. Please note the subtle BUT PROFOUND difference in these two statements. (And remember this next time you hear someone declare that it’s been proven that mercury does not increase risk of autism.) On the other hand, it is easier to say with honest conviction that A IS causal to B – a positive association is more compelling because there is data to support it, where as a negative could simply be negative because the design/experimental question was not one that might illuminate HOW and WHERE the association is strongest – in other words all we have is the absence of data and we don’t know if it’s because such data does not exist, or we simply did not ask the right question to find it.

This is why many in the medical profession are still saying that gluten is only problematic for a very few people. Most of the research I have seen claiming the self-proclaimed gluten-intolerant are mistaken, I find unconvincing, due to errors in how the question was posed/answered. Not only does the anecdotal/clinical experience of many physicians undermine the widespread view that gluten intolerance is fairly rare, but sometimes in unexpected research, we find additional evidence to undermine the conventional (mainstream) perspective on gluten. For example this paper looking at Iron Deficiency Anemia found many people who DID benefit from a gluten free diet, had tested negative by all the major tests currently used to diagnose gluten sensitivity – INCLUDING genetic testing.

The answer: Gluten! Some data suggest about a third of us have a measurable immune response to gluten. Furthermore, for a small subset it is not just gluten but all grains (but I think this is a much smaller group). Animal fats contain the most pro-inflammatory fatty acid known – arachidonic acid. Animal protein is known to generally increase levels of inflammation in the body, damage arterial blood vessels, increase blood cholesterol levels and increase blood pressure. So if someone notices improvement in specific symptoms as a result of getting more of their calories from meat, dairy or eggs and less from whole plant foods, (notice I specified “WHOLE” plant foods – meaning unprocessed) this dietary shift must be reducing or eliminating something that for that person is an even bigger contributor to inflammation or an immune reaction. (But this does not mean they aren’t also being injured by meat, dairy and eggs—it’s just not as obvious.) While all of these lower carb diets can improve some symptoms by removing gluten – and in fact all grains, Paleo does have one advantage over the other low-carb dogmas because most Paleo followers do three additional things that are health-promoting. 1) They eliminate processed carbs (like sugar, and flour which are also pro-inflammatory) 2) They eliminate or reduce dairy which is inflammatory, atherogenic, and allergenic for many, and 3) They tend to eat more green vegetables then they did before, and most Americans are already extremely deficient in protective phytochemicals/antioxidants from plants. (This is why we are able to have studies showing that heavy coffee drinkers have slightly improved survival over those who do not drink coffee. For many Americans, coffee is THE greatest source of phytochemicals in their diet!) But don’t be misled – the Paleo Diet is not only likely to be harmful to individuals long term, but if widely adopted would be devastating to the global poor, the environment and animals.

There are many good explanations for why some people trying a vegan diet, end up not feeling as good -- reasons which really have little to do with being vegan, and are completely fixable without giving up being vegan. One of the major reasons is that they simply aren’t eating enough calories. (Volume for volume plant foods don’t have as many calories - -so you do need to eat more to meet your energy needs.) But from my discussions with those who gave up being vegan, more often than not, their own narrative suggests to me that when they tried vegan and gave up meat and dairy they added more bread, pasta and processed foods in general – all things likely to increase their exposure to gluten. If someone is gluten sensitive, this could make them feel worse -- and if they don't know that gluten is making them feel badly -- they may blame it on the fact that they have cut out meat, dairy and eggs. This is why I encourage people transitioning to vegan, to also eliminate gluten at the same time, or at the very least, be careful to NOT eat MORE bread or pasta or other gluten containing foods (like faux meats!) The easiest way to do this, is to build meals around legumes (beans, peas and lentils) and vegetables, with small amounts of fresh raw nuts and seeds. Which reminds me of yet another problem with Paleo -- it discourages people from eating legumes which if rinsed well to eliminate possible cross contamination are not only gluten-free, but THE FOOD GROUP most associated with increased health and longevity in every population studied. They are also relatively inexpensive to produce, and thus more accessible for those with less money.